The research on city networks is becoming increasingly relevant in the field of International Relations (IR). Despite various approaches to conceptualize city networks, there is currently no universally accepted definition. Nevertheless, when conducting an analysis of international city networks (ICN) within the context of IR, there is a necessity to specify what ICNs actually are and whom they represent. Therefore, we define ICNs as “networks that consist of city members based in at least three countries, that may or may not include other types of actors, and whose focus can be on any given issue area of international relations (Jakobi et al. forthcoming).